1. Field of the Invention
This invention pertains to a padding body such as a foam padding body used in the formation of articles such as pillows, seat cushions, mattresses and mattress overlays.
2. Background Discussion
The prior art has introduced various padding body designs in attempting to achieve a versatile and comfortable padding body. For example, U.S. Pat. No. 4,809,374 to Saviez reveals a padding body formed by independent modular elements held in position by a plastic plate or grid. The plate or grid includes square meshes defining openings for receipt of the modular elements which can be varied in height and/or material. The modular elements are formed of a foam material and are designed to include a base section with one protuberance extending thereoff or a pair of protuberances extending to opposite sides of the base. The opening in the plate or grid is of a size which allows a protuberance to fit snugly therein but is smaller than the cross-section of the base.
U.S. Pat. No. 4,110,881 to Thompson illustrates the use of slots in a resilient article with the slots arranged in a rectangular grid. The slots vary in spacing and/or depth so as to tailor compressibility to accommodate for unequal loading.
The Thompson patent further illustrates how yield is influenced by compression as well as by a combination of forces including tension. The slits in the Thompson patent are described as assisting in the separation of compression and tension.
U.S. Pat. No. 4,042,987 to Rogers further reveals a mattress pad having a criss-crossing slit arrangement provided such that the shear stresses involved in transforming compressive loads into surface strain are fragmented.
The characteristics of a padding body required for achieving high comfort, while also allowing for good blood circulation in the user of the pad, include the following:
(1) A reduction in surface tension so as to avoid a shearing effect on the user of the padding body;
(2) A minimization in body surface contact while, at the same time, providing sufficient support;
(3) The creation of a therapeutic cradling effect between compressed and non-compressed modules while maintaining the shearing effect to a minimum and providing sufficient support;
(4) Maintaining an independent suspension among the modules of the padding for enhanced load bearing while allowing for load shifts and an ensurance of sufficient structural integrity;
(5) Forming the padding body of a material and of a design which is soft to the feel, provides sufficient support and avoids bottoming out.
The foregoing characteristics of a padding body are highly interrelated and adjustments to improve one of the above characteristics can lead to a degradation in one or more of the other characteristics. For example, the above-noted patent to Saviez, in addition to the problems associated with assembling the multitude of components, relies on a semi-rigid grid or plate. This semi-rigid grid or plate, while providing structural integrity, creates a stub like effect with regard to the upper protuberances. That is, the semi-rigid plate surrounding the protuberances limits the flexing ability at the foundation of each protuberance during shifts in loading. In addition, the contact between the essentially non-giving, semi-rigid plate and the individual modules leads to the development of shearing forces within each module which can be transferred to the person in contact with the module. The ability of the modules to flex with shifting loads can be enhanced by lessening the cross-sectional periphery of each protuberance and/or increasing the length of the protuberances, but that would lead to degradation of other padding characteristics such as a firm, non-wobbly support. Also, the use of a semi-rigid plate with edges extending about the periphery would require additional padding about the edges if the padding body is to be used as a pillow or seat cushion where contact with the edge of the padding occurs.
The rectangular grid of modules disclosed in the above-noted Thompson and Rogers patents, while providing for a reduction in tension, fail to minimize body contact. Also, the close proximity of each module lessens the independent suspension of each module due to interaction between the modules during compression (bulging) and non-vertical loading.